Determination of the Effects of Fine- Grained Sediment and Other Limiting Variables on Trout Habitat for Selected Streams in Wisconsin By Barbara C. Scudder, Jeffery W. Selbig, and Robert J. Waschbusch U.S. GEOLOGICAL SURVEY Open-File Report 00-435 Prepared in cooperation with the WISCONSIN DEPARTMENT OF NATURAL RESOURCES Middleton, Wisconsin 2000 uses science for a changing world U.S. DEPARTMENT OF THE INTERIOR BRUCE BABBITT, Secretary U.S. GEOLOGICAL SURVEY Charles G. Groat, Director Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. For additional information write to: Copies of this report can be purchased from: District Chief U.S. Geological Survey U.S. Geological Survey Branch of Information Services 8505 Research Way Box 25286 Middleton, Wl 53562-3586 Denver, CO 80225-0286 CONTENTS Abstract................................................................................................................................................................................. 1 Introduction........................................................................................................................................................................... ] Purpose and scope....................................................................................................................................................... 2 Study area.................................................................................................................................................................... 2 Acknowledgments....................................................................................................................................................... 4 Methods................................................................................................................................................................................. 4 Data collection............................................................................................................................................................ 4 Application of Habitat Suitability Index models ........................................................................................................ 6 Results................................................................................................................................................................................... 7 KickapooRiver watershed.......................................................................................................................................... 7 Trempealeau River watershed..................................................................................................................................... 14 Chippewa River watershed ......................................................................................................................................... 16 Summary and conclusions .................................................................................................................................................... 16 References............................................................................................................................................................................. 18 Appendixes: 1. Locations of samples reaches for the 11 study streams in the Kickapoo, Trempealeau, and Chippewa watersheds of Wisconsin ........................................................................................................................................ 22 2. Suitability index variables for the brook and brown trout Habitat Suitability Index models and sources of data ........................................................................................................................................................ 24 FIGURES 1. Map showing location of the Kickapoo, Trempealeau, and Chippewa, watersheds in Wisconsin together with 11 study streams and location of sampling stations where brook and brown trout habitat were examined by Habitat Suitability Index analysis........................................................................................................................... 3 2. Graph showing response curves showing how the HSI for brook trout is affected when the percentage of fine-grained sediment (<3 mm) in spawning areas varies with the percentage of substrate for winter and escape cover station 1, Lowes Creek August 1991............................................................................................... 6 TABLES 1. Percent agriculture in subwatersheds of the 11 study streams.................................................................................. 4 2. Summary of habitat data collected for Kickapoo and Trempealeau watersheds during 1990 and Chippewa watershed during 1991 .......................................................................................................................... 8 3. Number of brook trout collected and results of Habitat Suitability Index model for brook trout in Kickapoo and Trempealeau watersheds in 1990 and Chippewa watershed in 1991 before and after computer-simulated modification of the percentage of fine sediment in spawning and riffle-run areas ................................................ 10 4. Number of brown trout collected and results of Habitat Suitability Index model for brown trout in Kickapoo and Trempealeau watersheds in 1990 and Chippewa watershed in 1991 before and after computer-simulated modification of the percentage of fine sediment in spawning and riffle-run areas ................................................ 11 5. Life Requisite Suitability Index (LRSI) and Habitat Suitability Index (HSI) values for brown trout in 11 Wisconsin streams during 1990 and 1991.............................................................................................................. 13 CONTENTS III CONVERSION FACTORS AND ABBREVIATED WATER-QUALITY UNITS Multiply_________________By_______________To Obtain inch (in.) 25.4 millimeter foot (ft) 0.3048 meter mile (mi) 1.61 kilometer pound (Ib) 453,600 milligram tons/mi2 0.3503 tonnes/km2 (tonnes per square kilometer) Temperature in degrees Celsius (°C) can be converted to degrees Fahrenheit (°F) by use of the following equation: °F=1.8(°C) + 32. Abbreviated water-quality units used in this report: Chemical concentrations and water temperature are given in metric units. Chemical concentration is given in milligrams per liter (mg/L) or micrograms per liter (Ug/L). Milligrams per liter is a unit expressing the concentration of chemical constituents in solution as weight (milligrams) of solute per unit volume (liter) of water. One thousand micrograms per liter is equivalent to one milligram per liter. For concentrations less than 7.000 mg/L. the numerical value is the same as for concentrations in parts per million. Other units of measurement used in this report are microsiemens per centimeter at 25°Celsius (nS/cm), micrometers IV CONVERSION FACTORS AND ABBREVIATED WATER-QUALITY UNITS Determination of the Effects of Fine-Grained Sediment and Other Limiting Variables on Trout Habitat for Selected Streams in Wisconsin By Barbara C. Scudder, Jeffery W. Selbig, and Robert J. Waschbusch Abstract water streams in southern and central Wisconsin. Brown trout may be tolerant of streams that have Two Habitat Suitability Index (HSI) models, devel­ become unsuitable for brook trout because of increased oped by the U.S. Fish and Wildlife Service, were used summer temperatures and turbidity from land-manage­ to evaluate the effects of fine-grained (less than 2 milli­ ment activities (Becker, 1983). meters) sediment on brook trout (Salvelinusfontinalis, Mitchill) and brown trout (Salmo trutta, Linnaeus) in 11 Reproductive success of brook trout and brown streams in west-central and southwestern Wisconsin. trout decreases with increasing amounts of fine-grained Our results indicated that fine-grained sediment limited sediment in spawning areas (Peters, 1965; Harshbarger, brook trout habitat in 8 of 11 streams and brown trout 1975; Waters, 1995). In this report, fine-grained sedi­ habitat in only one stream. Lack of winter and escape ment is less than 2 mm in diameter. This includes sand, cover for fry was the primary limiting variable for silt, and clay. Spawning of brook and brown trout occurs brown trout at 61 percent of the sites, and this factor also from October to December or early January in redds limited brook trout at several stations. Pool area or qual­ made in gravel bottoms of Wisconsin streams. Redds ity, in stream cover, streambank vegetation for erosion often are located in riffle areas or at the tail of pools control, minimum flow, thalweg depth maximum, water where upwelling or downwelling water currents in temperature, spawning substrate, riffle dominant sub­ gravel ensure optimal stream velocities and dissolved- strate, and dissolved oxygen also were limiting to trout oxygen concentrations for embryos (Avery and Nierm- in the study streams. Brook trout appeared to be more eyer, 1999; Brynildson and others, 1963; Becker, 1983). sensitive to the effects of fine-grained sediment than Location of redds in these areas also minimizes harmful brown trout. The models for brook trout and brown trout effects of sedimentation because fine-grained sediments appeared to be useful and objective screening tools for are generally rapidly removed to other stream areas by identifying variables limiting trout habitat in these the